Upgrade with minimal downtime

Registered by John Garbutt

Clouds are expected to be always available and involve large numbers of servers. This blueprint looks how we can perform upgrades with minimal disruption.

Goals for the upgrade are:
- where possible, transparent to the cloud users
- minimal instance downtime or instance connectivity loss
- ability to rollback to a pre-upgrade state if things fail
- ability to upgrade from v2 to v4 without having to do upgrade to v3 first (supporting at least two versions forward/back?)
- define what we mean by v2 and v4. It could mean 2012.1 -> 2012.3 (etc.), but what about sprint releases, what about bug fix releases to major versions (http://summit.openstack.org/sessions/view/106)

Blueprint information

Status:
Complete
Approver:
Vish Ishaya
Priority:
High
Drafter:
Citrix OpenStack development team
Direction:
Approved
Assignee:
Nova Upgrades Team
Definition:
Obsolete
Series goal:
None
Implementation:
Unknown
Milestone target:
None
Completed by
Vish Ishaya

Related branches

Sprints

Whiteboard

This needs to be broken out into concrete steps and blueprints by the upgrades team --Vish

(?)

Work Items

Dependency tree

* Blueprints in grey have been implemented.